, oo 
n8g0.] RAFTER AND MALLORY—ENDEMIC OF TYPHOID FEVER. 79 
-determined o.21 and o.19 grains per U.S. gallon, or o.20as amean. We 
must conclude from this close agreement of results reached by two 
-chemists, working independently, that there is no question as to the 
-essential accuracy of the result in 1889. 
The great reputation of Professor Leeds and the evident painstak- 
ing character of all the work emanating from his laboratory, renders it 
‘impossible to successfully impeach his work in 1881, and we are led, 
therefore, to the belief, that the evidence of an increase in the organic 
-contamination of Hemlock lake water is conclusive. 
We urge this for no other reason than to indicate the necessity for 
“strict protection of the Hemlock water shed. The city of Rochester 
has in Hemlock lake a most admirable water supply, of great natural 
purity, and the legitimate conclusion to be drawn from such a discussion 
-as the present one is that every effort should be made to keep Hemlock 
dake, in the matter of purity, in its original state. 
The causes of the gradually increasing contamination are (1) the 
growth since 1877 of a considerable summer population about the lake, 
and (2) additional soil contamination in the village of Springwater and 
its consequent influence on the purity of the influent waters of the 
Springwater creek. 
As to the first, we may say that while we recognize the value of the 
-care which has been exercised about the shores of Hemlock lake itself 
since 1885, nevertheless the presence there of a summer population of 
from eight hundred to twelve hundred people must inevitably cause 
considerable organic contamination. Relative to the second source of 
evident increase of organic contamination, the analyses made last fall 
by Drs. Ernst and Harrington enable us to present more certain 
evidence. 
Referring to Dr. Harrington’s chemical analysis No. 3, of water 
‘from the Lime-Kiln Gull creek, at the Advent church (see table page 
-71) we find free ammonia present to the amount of 0,0003 parts in 
£00,000. Analysis No. 11, of water from the same stream at north end 
-of village, gives free ammonia to the amount of 0.0014 parts in 100,000; 
-or, the result of this stream flowing from Mill street to north end of 
village is an increase of free ammonia four and two-thirds times. Again, 
albuminoid ammonia at the Advent church was 0.0924 parts in 100,000, 
while at north end of village it was 0.0046 parts in 100,000; or, 
albumineid ammonia was nearly doubled as the result of flowing through 
Springwater village. In the same way all the other elements show some 
‘increase, as, for instance, the chlorine and fixed, volatile and total 
-residues. 
